GB2382108A

GB2382108A - Vibration isolating arrangement for a fan of an airconditioning unit

Info

Publication number: GB2382108A
Application number: GB0220356A
Authority: GB
Inventors: Atsushi Edayoshi; Kazuhide Tsukiori; Takashi Watanabe
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2001-09-03
Filing date: 2002-09-02
Publication date: 2003-05-21
Anticipated expiration: 2022-09-02
Also published as: GB2382108B; CN1403720A; CN1215264C; GB0220356D0

Abstract

A vibration isolating arrangement for a fan 3 comprises a boss 8 which is made up of an inner cylinder 9, an outer cylinder 10 and an elastic body 11. The elastic body 11 is adhered and fixed between the inner cylinder 9 and the outer cylinder 10. The inner cylinder 9 is attached to a shaft 7 of a fan motor 2, and the fan 3 is attached to the outside of the boss 8. An outer portion of the inner cylinder 9 and an inner portion of the outer cylinder 10 vary in diameter in an axial direction, and this variation may form a taper 13. The fan 3 may be a centrifugal fan of an airconditioning unit. An alternative vibration isolating arrangement for a fan is shown in figures 7-9.

Description

A VIBROISOLATING STRUCTURE OF A BLOWER, AND AN AIR CONDITIONER Background of the Invention Field of the Invention The present invention relates to a vibroisolating structure of a blower composed of a fan and a fan motor.

Description of the Related Art Figs. 6A and 6B show sectional views of a conventional blower disclosed in Japanese Unexamined Utility Model Publication No. 1-85497 as an example. In Figs. 6A and 6B, the following are provided: a fan motor 2, a centrifugal fan 3 driven by the fan motor 2, a shaft 7 of the fan motor, and a boss part 8. The boss part 8 is composed of an inner cylinder 9, an outer cylinder 10, and an elastic body 11. The elastic body 11 has been adhered to the inner cylinder 9 and the outer cylinder 10 by way of vulcanization.

In the blower configured as mentioned above, the shaft 7 of the fan motor which is fit in the inner cylinder 9 and fixed with a screw etc. , transmits torque of the fan motor 2 to the centrifugal fan 3. The elastic body 11 absorbs vibrations caused by a magnetic fluctuation and a torque fluctuation which are generated with a speed control of the fan motor 2. Consequently, the elastic body 11 prevents an unusual sound from generating by the vibrations.

The boss part 8 needs to have strength sufficient enough to transmit the rotation of the fan motor 2. The main loads which the boss part 8 receives are the rotation torque generated by the fan motor 2, the thrust which the centrifugal fan 3 receives in the direction of the axis from fluid, and a self-weight of the centrifugal fan 3.

In the boss part 8, the elastic body 11 is a part with a low strength. In the elastic body 11, the maximum stress is generated by the above-mentioned loads at the adhesion side with the inner cylinder 9, and the main constituent of the stress is a shearing stress. When the adhesion is inadequate, there is a possibility that unusual sound might be generated because of the adhesion side being destroyed by the shearing stress. Therefore, in the conventional blower disclosed in the Japanese Unexamined Utility Model Publication No. 1-85497, a flute 19 is formed on the inner cylinder 9 in order to disperse a part of the generated stress into a compressive stress or a tensile stress.

Problems to be solved by the Invention Since the conventional blower is structured as mentioned above, the inner cylinder 9 and the outer cylinder 10 are made to be thin in order to enhance the vibroisolating effect in the limited space. Then, the depth of the flute 19 is shallow, so that the shearing stress might become dominant (most influential), which may break the adhesion side of the elastic body 11 and the inner cylinder 9 and result in generating the unusual sound as mentioned above.

Summary of the Invention One of objects of the present invention is to solve the above problem and to provide a vibroisolating structure of a blower, a boss part of a fan, and an air conditioner where the shearing stress at the adhesion side of the elastic body in the boss part can be reduced and the generation of the unusual sound can be suppressed without lowering the vibroisolating effect.

Moreover, another object of the present invention is to provide a vibroisolating structure of a blower, a boss part of a fan, and an air conditioner where the rotation is not impeded even when the adhesion of the elastic body in the boss part is inadequate.

According to one aspect of the present invention, a vibroisolating structure of a blower, including a fan motor, a shaft for transmitting torque of the fan motor, a boss part having an inner cylinder, being circular, engaged with the shaft, an outer cylinder, being circular, stationed outside of the inner cylinder, and an elastic body adhered and fixed between the inner cylinder and the outer cylinder, and a fan provided outside of the boss part, the vibroisolating structure of the blower includes a part whose diameter varies along an axial direction, formed in at least a portion of an outer circumference of the inner cylinder and an inner circumference of the outer cylinder, in order to make a compressive stress act on the elastic body by a load dominant in loads in the axial direction acting on the boss part.

According to another aspect of the present invention, a vibroisolating structure of a blower including a fan motor, a shaft for transmitting torque of the fan motor, a boss part having an inner cylinder, being circular, engaged with the shaft, an outer cylinder, being circular, stationed outside of the inner cylinder, and an elastic body adhered and fixed between the inner cylinder and the outer cylinder, and a fan provided outside of the boss part, the vibroisolating structure

of the blower includes the elastic body whose surface has a smooth curved incline to satisfy a relation ofB2 > B > B1 where B denotes a height of a section of an assumed cylinder whose center is the shaft of the fan motor, Bl denotes a height of the elastic body at an outer cylinder side, and B2 denotes a height of the elastic body at an inner cylinder side.

The above-mentioned and other objects, features, and advantages of the present invention will be made more apparent by reference to the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, Fig. 1 shows a sectional view of a ceiling embed type air conditioner according to Embodiment 1; Fig. 2A shows a sectional view of a blower according to Embodiment 1; Fig. 2B shows a sectional view of a blower according to Embodiment 1 ; Fig. 3 shows a sectional view of a blower in which the attachment of the boss part has been changed, according to Embodiment 1 ; Fig. 4A shows a sectional view of a blower according to Embodiment 2; Fig. 4B shows a sectional view of a blower according to Embodiment 2; Fig. 5 shows an enlarged sectional view of projections, according to Embodiment 2; Fig. 6A shows a sectional view of a conventional blower; Fig. 6B shows a sectional view of a conventional blower; Fig. 7 shows a sectional view of a ceiling embed type air conditioner according to Embodiment 3; Fig. 8 shows a sectional view of a blower according to Embodiment 3; and Fig. 9 shows a sectional view of a blower according to Embodiment 4.

Detailed Description of the Preferred Embodiments Embodiments of the present invention will now be explained referring to the figures. Embodiment 1.

Embodiment 1 is described with reference to Figs. 1 through 3. Fig. 1 shows a sectional view of a ceiling embed type air conditioner with which a blower is attached. Figs. 2A and 2B show sectional views of the blower of the air conditioner, and Fig. 3 shows a sectional view of another blower in which the attachment of the boss part has been changed.

In Fig. 1, the following are provided: a case 1 configuring an air path of the ceiling embed type air conditioner, a fan motor 2 attached to the case 1 with a bolt etc. , a centrifugal fan 3 made of plastic driven by the fan motor 2, a heat exchanger 4 of refrigerating cycle installed on the periphery of the centrifugal fan 3, a suction part 5 for sucking indoor air, and blow-off parts 6 for blowing off the air heat-exchanged with the heat exchanger 4. This ceiling embed type air conditioner is installed indoors with the suction part 5 and the blow-off part 6 being exposed at the ceiling side and the case 1 being embedded in the ceiling.

The operation of the blower of the air conditioner will now be explained. First, the centrifugal fan 3 connected to the shaft of the fan motor 2 is rotated by torque of the fan motor 2. At this time, the air flows as follows: Air is sucked from the suction part 5 of the air conditioner, sent in the direction of the outer circumference from the center of the centrifugal fan 3, heat-exchanged by passing through the heat exchanger 4, and cooled or warmed to be blown off from the blow-off part 6.

In Figs. 2A and 2B, the following are provided: a shaft 7 of the fan motor, and a boss part 8. The boss part 8 is composed of an inner cylinder 9 and an outer cylinder 10 which are circular and made of metal, and an elastic body 11 molded by way of vulcanizing between the inner cylinder 9 and the outer cylinder 10. The elastic body 11 is adhered with the adhesive beforehand applied to the inner cylinder 9 and the outer cylinder 10. The boss part 8 is included at the time of molding the centrifugal fan 3, and the outer part of the boss part 8 is cast by resin to be one molded body. The shaft 7 of the fan motor is fit in the inside of the inner cylinder 9 and is fixed with a nut 12.

The outer circumference of the inner cylinder 9 and the inner circumference of the outer cylinder 10 of the boss part 8 receive loads in the axial direction which are a self-weight of the centrifugal fan 3 (in the direction of arrow 14) and a thrust which the centrifugal fan 3 receives from fluid (in the opposite direction of the self-weight). In the case of the ceiling embed type air conditioner shown in Fig. 1, the self-weight of the centrifugal fan 3, in the direction of the

arrow 14, is dominant. Therefore, a taper 13 is provided which makes the outer diameter of the inner cylinder and the inner diameter of the outer cylinder long in the direction of the arrow 14.

According to the above structure, since compressive stresses are always generated by the load in the direction of the axis, even when the adhesion of the inner cylinder 9 or the outer cylinder 10, and the elastic body 11 is inadequate, the adhesion side of the elastic body 11 becomes hard to break. Moreover, comparing with the flute formed on the inner cylinder according to the conventional art, the taper (a part whose diameter varies along the axial direction) can dispersively receive the force. Therefore, a stress concentration is hard to generate. In this case, the tapers 13 are provided on both the inner cylinder 9 and the outer cylinder 10. It is also acceptable to provide the taper, depending upon the stresses generated on the inner cylinder 9 or the outer cylinder 10, on either of the inner cylinder 9 and the outer cylinder 10 which has the larger stress.

Although the form where the tapers 13 are provided on the outer diameter of the inner cylinder and the inner diameter of the outer cylinder has been described, it is not limited to the taper 13. Any form is acceptable as long as the outer diameter of the inner cylinder or the inner diameter of the outer cylinder changes in the axial direction in order that a compressive stress can act on the elastic body 11 by the load in the axial direction.

Moreover, it is also acceptable to provide the taper 13 on the whole of the outer diameter of the inner cylinder and the inner diameter of the outer cylinder, or to provide the taper 13 on a part of the outer diameter of the inner cylinder and the inner diameter of the outer cylinder.

According to Embodiment 1, the outer cylinder 10 and the centrifugal fan 3 are made from different materials. It is also acceptable to form the outer cylinder 10 to be one mold body with the centrifugal fan 3 by means of utilizing the elastic body made of elastomer type which can be molded together with plastic, for instance.

Further, according to Embodiment 1, the centrifugal fan 3 and the boss part 8 are formed to be one mold body. It is also acceptable to fix the boss part 8, as another part, to the centrifugal fan 3 with screws, rivets 15, etc as shown in Fig. 3. According to this method, it is acceptable for the centrifugal fan 3 to be made of metal, such as aluminum and steel.

In Embodiment 1, the blower of the ceiling embed type air conditioner, in which the fan

motor 2 and the centrifugal fan 3 are stationed in the longitudinal direction, has been described as one example. However, the present invention is not limited to such a blower. For example, the present invention can also be applied to the blower where the fan motor and the fan are horizontally stationed and a thrust which the fan receives from fluid acts as a load in the axial direction. Then, it is possible to restrain the adhesion side of the elastic body from being destroyed by the thrust which the fan receives from the fluid.

Furthermore, although the case that the centrifugal fan is used as a fan has been described, it is also acceptable to use a multiblade fan or a propeller fan.

Embodiment 2.

Embodiment 2 will now be described with reference to Figs. 4A, 4B and 5. Figs. 4A and 4B show sectional views of a blower and Fig. 5 shows an enlarged view of adjacency of a projection 16. As shown in Fig. 4B, three projections 16 are formed on each of the outer circumference of the inner cylinder 9 and the inner circumference of the outer cylinder 10 of the boss part 8 in addition to the taper explained in Embodiment 1.

As shown in Fig. 5, in order not to receive a stress concentration, the projection 16 is shaped to have an arced projection tip 17, and a projection root 18 on the outer circumference of the inner cylinder 9 and the inner circumference of the outer cylinder 10 is shaped to be a form of letter R. Although the projection tip 17 and the projection root 18 are in the shape of R in the present Embodiment, what is needed is just a curved surface linked smoothly.

Moreover, the number of the projections 16 is not specifically limited. However, in order to keep the rotary balance, it is desirable to provide the projections at two or greater than two places and to arrange the projections in order not to lose the balance.

By dint of providing the projections 16 as stated above, a propulsive force can be obtained and rotation of the centrifugal fan 3 is not impeded because the projections 16 push the elastic body 11 in the direction of rotation even when the adhesion of the inner cylinder 9 or the outer cylinder 10, and the elastic body 11 is inadequate.

Furthermore, it is acceptable to independently execute each of Embodiments 1 and 2, or to carry out both of Embodiments 1 and 2 together jointly.

Embodiment 3.

Embodiment 3 will now be explained referring to Figs. 7 and 8. Fig. 7 shows a sectional view of a ceiling embed type air conditioner, and Fig. 8 shows a sectional view of a blower.

In Fig. 7, the following are provided: a case 1 configuring an air path, a fan motor 2 attached to the case 1 with a bolt etc. , a centrifugal fan 3 made of plastic driven by the fan motor 2, a heat exchanger 4 of refrigerating cycle installed on the periphery of the centrifugal fan 3, a suction part 5 for sucking indoor air, and blow-off parts 6 for blowing off the air heat-exchanged with the heat exchanger 4. This ceiling embed type air conditioner is installed indoors with the suction part 5 and the blow-off part 6 being exposed at the ceiling side and the case 1 being embedded in the ceiling.

The operation of the blower of the air conditioner will now be explained. First, the centrifugal fan 3 connected to the shaft of the fan motor 2 is rotated by torque of the fan motor 2.

At this time, the air flows as follows: Air is sucked from the suction part 5 of the air conditioner, sent in the direction of the outer circumference from the center of the centrifugal fan 3, heat-exchanged by passing through the heat exchanger 4, and cooled or warmed to be blown off from the blow-off part 6.

In Fig 8, the following are provided: a shaft 7 of the fan motor, and a boss part 8. The boss part 8 is composed of an inner cylinder 9 and an outer cylinder 10 which are circular and made of metal, and an elastic body 11 molded by way of vulcanizing between the inner cylinder 9 and the outer cylinder 10. The elastic body 11 is adhered with the adhesive applied beforehand to the inner cylinder 9 and the outer cylinder 10. The boss part 8 is included at the time of molding the centrifugal fan 3, and the outer part of the boss part 8 is cast by resin to be one molded body. The shaft 7 of the fan motor is fit in the inside of the inner cylinder 9 and is

fixed with a nut 12. In order not to generate a stress concentration at the attaching parts between the elastic body 11 and the inner cylinder 9, and the elastic body 11 and the outer cylinder 10, the processing such as forming a shape of a letter R is performed.

Assuming a cylinder whose center is the shaft 7 of the fan motor and whose radius is R in the elastic body 11 and the cylinder is sectioned, the height B of the section of the cylinder is now explained. Rotation torque of the fan motor 2 is dominant in forces acting on the boss part.

ri

A shearing stress-c generated by the rotation torque, which is defined to be torque T, can be expressed as follows: 'r = T/ (2 7r R2 B)................... (I) As shown in the expression (1), since the shearing stress T is in inverse proportion with the square of the radius R, it is possible to decrease B corresponding to an increase of the radius R. In other words, in order to have constant shearing stress, the height B of the elastic body 11 is changed depending upon the radius R.

Roughly describing, the form whose surface has a smooth curved incline to satisfy B2 > B > Bl is acceptable as the elastic body 11. In this case, B denotes a height of the section of the cylinder assumed to be sectioned to have its center to be the shaft 7 of the fan motor and its radius to be R. Bl denotes the height of the elastic body 11 at the outer cylinder 10 side, and B2 denotes the height of the elastic body 11 at the inner cylinder 9 side.

By keeping the elastic body 11 of the form above described, it is possible to effectively reduce the volume of rubber composing the elastic body 11, without lowering the strength of the elastic body 11. Then, that makes the spring constant low. Therefore, the effect of absorbing vibrations of the fan motor 2 can be enhanced.

Embodiment 4.

Fig. 9 shows a sectional view of a blower according to Embodiment 4, where the form of the elastic body is different from that described in the above Embodiment. When it is difficult to keep the above described form of the elastic body 11 in molding, it is acceptable to have the shape shown in Fig. 9 where the height of the elastic body 11 at the outer cylinder 10 side is shorter than that at the inner cylinder 9 side, and the elastic body 11 has a straight surface shaped by connecting the edges of the heights of the outer cylinder 10 and the inner cylinder 9 with straight lines. Then, it becomes easy to mold the elastic body 11.

Effects of the Invention According to one aspect of the vibroisolating structure of the blower of the present invention, the part whose diameter varies along the axial direction is formed in at least a portion of the outer circumference of the inner cylinder and the inner circumference of the outer

cylinder, in order to make a compressive stress act on the elastic body by a load dominant in loads in the axial direction acting on the boss part. In other words, in at least a part of the outer circumference of the inner cylinder and the inner circumference of the outer cylinder, a diameter varies along the axial direction, in order to make a compressive stress act on the elastic body by a load dominant in loads in the axial direction acting on the boss part. Thus, as the adhesion side of the elastic body is always pushed by the load dominant in the axial direction, the adhesion side becomes hard to break and a generation of an unusual sound can be suppressed.

According to another aspect of the vibroisolating structure of the blower of the present invention, as the part whose diameter varies along the axial direction is a taper, manufacturing the boss part can be easily executed.

According to another aspect of the vibroisolating structure of the blower of the present invention, the fan motor and the fan are stationed in the longitudinal direction and the load dominant in loads in the axial direction acting on the boss part is a self-weight of the fan.

Thus, as the adhesion side of the elastic body is pushed by the self-weight of the fan, the adhesion side becomes hard to break and a generation of an unusual sound can be suppressed.

According to another aspect of the vibroisolating structure of the blower of the present invention, since the centrifugal fan is used as the fan, the vibroisolating structure can be applied to a blower of a ceiling embed type air conditioner.

According to another aspect of the vibroisolating structure of the blower of the present invention, the fan motor and the fan are horizontally stationed and the load dominant in loads in the axial direction acting on the boss part is a thrust which the fan receives from fluid. Thus, since the adhesion side of the elastic body is pushed by the thrust which the fan receives from fluid, the adhesion side becomes hard to break and a generation of an unusual sound can be suppressed.

According to another aspect of the vibroisolating structure of the blower of the present invention, comparing stresses generated on the outer circumference of the inner cylinder and the inner circumference of the outer cylinder, the part whose diameter varies along the axial direction is provided on either one of the outer circumference of the inner cylinder and the inner

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circumference of the outer cylinder which has a larger stress. Thus, a generation of an unusual sound can be suppressed, and the structure can be simplified.

According to another aspect of the present invention, an air conditioner applies the vibroisolating structure of the blower to its blower. Thus, a generation of an unusual sound in the blower of the air conditioner can be suppressed.

Having thus described several particular embodiments of the invention, various alterations, modifications, and improvements will readily occur to those skilled in the art.

Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description is by way of example only, and not intended to be limiting. The invention is limited only as defined in the following claims and the equivalents thereto.

Claims

What is claimed is:

1. A vibroisolating structure of a blower which includes a fan motor, a shaft for transmitting torque of the fan motor, a boss part having an inner cylinder, being circular, engaged with the shaft, an outer cylinder, being circular, stationed outside of the inner cylinder, and an elastic body adhered and fixed between the inner cylinder and the outer cylinder, and a fan provided outside of the boss part, the vibroisolating structure of the blower comprising: a part whose diameter varies along an axial direction, formed in at least a portion of an outer circumference of the inner cylinder and an inner circumference of the outer cylinder, in order to make a compressive stress act on the elastic body by a load dominant in loads in the axial direction acting on the boss part.

2. The vibroisolating structure of the blower of claim 1, wherein the part whose diameter varies along the axial direction, formed in at least a portion of the outer circumference of the inner cylinder and the inner circumference of the outer cylinder is a taper.

3. The vibroisolating structure of the blower of claim 1, wherein the fan motor and the fan are stationed in a longitudinal direction and the load dominant in loads in the axial direction acting on the boss part is a self-weight of the fan.

4. The vibroisolating structure of the blower of claim 3, wherein the fan is a centrifugal fan.

5. The vibroisolating structure of the blower of claim 1, wherein the fan motor and the fan are horizontally stationed and the load dominant in loads in the axial direction acting on the boss part is a thrust which the fan receives from fluid.

6. The vibroisolating structure of the blower of claim 1, wherein the part whose diameter varies along the axial direction is provided on either one of the outer circumference of the inner cylinder and the inner circumference of the outer cylinder which has a larger stress, depending upon stresses generated on the outer circumference of the inner cylinder and the inner circumference of the outer cylinder.

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7. An air conditioner in which the vibroisolating structure of the blower of claim 1 is applied to a blower.

8. A vibroisolating structure of a blower which includes a fan motor, a shaft for transmitting torque of the fan motor, a boss part having an inner cylinder, being circular, engaged with the shaft, an outer cylinder, being circular, stationed outside of the inner cylinder, and an elastic body adhered and fixed between the inner cylinder and the outer cylinder, and a fan provided outside of the boss part, the vibroisolating structure of the blower comprising: the elastic body whose surface has a smooth curved incline to satisfy a relation of B2 > B > Bl where B denotes a height of a section of an assumed cylinder whose center is the shaft of the fan motor, B 1 denotes a height of the elastic body at an outer cylinder side, and B2 denotes a height of the elastic body at an inner cylinder side.

9 The vibroisolating structure of the blower of claim 8, wherein the B is changed depending upon R in order to have constant shearing stress r = T/ (2 X R2 B), where the B is the height of the section of the assumed cylinder whose center is the shaft of the fan motor and whose radius is the R, and T is rotation torque of the fan motor.

10. The vibroisolating structure of the blower of claim 8, wherein the height of the elastic body at the outer cylinder side is shorter than the height of the elastic body at the inner cylinder side, and the elastic body has a form shaped by connecting edges of the height of the elastic body at the outer cylinder side and the height of the elastic body at the inner cylinder side with straight lines.